Merge pull request #22430 from shulaoda/05-23-fix_hir-ty_saturate_float-to-uint_cast_in_const_eval

fix(hir-ty): saturate float-to-uint cast in const eval

Author: lnicola

crates/hir-ty/src/consteval/tests.rs

@@ -287,6 +287,9 @@ fn floating_point_casts() {
     check_number(r#"const GOAL: i8 = (0./0.) as i8"#, 0);
     check_number(r#"const GOAL: i8 = (1./0.) as i8"#, 127);
     check_number(r#"const GOAL: i8 = (-1./0.) as i8"#, -128);
+    check_number(r#"const GOAL: u8 = (1./0.) as u8"#, 255);
+    check_number(r#"const GOAL: u8 = 256.0f32 as u8"#, 255);
+    check_number(r#"const GOAL: u16 = 1e10f32 as u16"#, 65535);
     check_number(r#"const GOAL: i64 = 1e18f64 as f32 as i64"#, 999999984306749440);
 }
 

crates/hir-ty/src/mir/eval.rs

@@ -1594,7 +1594,7 @@ impl<'a, 'db: 'a> Evaluator<'a, 'db> {
                         let max = 1i128 << (dest_bits - 1);
                         (max - 1, -max)
                     } else {
-                        (1i128 << dest_bits, 0)
+                        ((1i128 << dest_bits) - 1, 0)
                     };
                     let value = (value as i128).min(max).max(min);
                     let result = value.to_le_bytes();